Projecting multimedia files from mobile devices onto a large display device, for example, a TV, via a set top box (STB) is a popular application service. Thus, users can watch a movie or share photos with friends through the TV. Traditionally, users select the name of a STB through a screen of a mobile terminal, and the mobile terminal projects multimedia files or contents onto a display device connecting with the STB. However, when there are multiple large display devices connecting with STBs, it is easy to choose a wrong display device for data projection.